The present invention relates to a rotary head-type digital audio tape recorder, namely, a so-called R-DAT. In particular, the invention relates to an R-DAT in which the reading of TOC (Table of Contents) information is inhibited by detecting the state of a tab provided for preventing accidental erasure of a cassette played on the R-DAT.
As is well known, an R-DAT (abbreviated to DAT hereinafter) is required to perform various functions such as a renumbering function in which program numbers (PNOs) which are not recorded in sequence and which would otherwise result in overlap, missing numbers, etc., are re-recorded in a continuous sequence in an after-recording process, and a so-called TOC renumbering function for collecting TOC information (U-TOC) during the above renumbering operation and writing the TOC information in a subcode region of a top program, that is the program which is recorded first on the tape. FIG. 4 shows a recording format of the TOC information for a TOC renumbering operation.
FIG. 1 shows the construction of a conventional DAT. In this figure, reference numeral 1 indicates a mechanical block including a mechanism for effecting the running of the magnetic tape 2, a rotary drum 3 for helical scanning of the tape 2, magnetic heads 4a and 4b for recording/reproduction and which are attached to a rotary drum 3, a pinch roller 5, a capstan 6, a supply reel 7, and a take-up reel 8.
Further, reference numeral 9 indicates a head changeover switch for switching between magnetic heads 4a and 4b as the rotary drum 3 rotates; 10, a recording/reproduction changeover switch for switching between recording and reproduction modes; 11, an amplifier used for reproduction; 12, an amplifier used for recording; 13, a signal processing circuit including various circuits such as an encoder, decoder, etc.; 14, an A/D converter; 15, a D/A converter; 16, a system controller composed of a microcontroller, etc., for controlling the various operations of the overall apparatus; 17, an input device for instructing various operating commands from the exterior to the system controller 16; 18, a display device for displaying the operating state of the apparatus; 19 a TOC information memory for storing the TOC information; and 20, a flag for storing and indicating the detection of a read-out area on the magnetic tape 2 by an end mark operation or an end search operation.
The operation of the conventional DAT constructed as described above will now be described.
In the conventional DAT, the aforementioned TOC renumbering operation is executed in the case where a renumbering operation is executed subsequent to a so-called end mark operation for recording PNO="OEE" (read-out area) indicative of a terminal portion on the tape, or a so-called end search operation for searching for PNO="OEE" (read-out area) indicative of the terminal portion recorded on the tape. Accordingly, the end mark operation and the end search operation will first be described prior to a description of the renumbering processing.
The end mark operation is an operation for recording on the tape PNO="OEE" (read-out area) indicative of the recording terminal portion, which is prescribed by the subcode format for the R-DAT as mentioned above. This operation is normally a processing operation executed after completion of overwriting, etc.
When the end mark operation is instructed from the input device 17, the system controller 16 clears the internal flag 20 (="0") and outputs "OEE" representing the read-out area a the PNO to the signal processing circuit 13. Then, the signal processing circuit 13 and the mechanical block 1 are set for the recording operating mode, and PNO="OEE" representing the read-out area is recorded for 9 seconds in the subcode region of the recording terminal portion of the tape in which overwriting is to be performed (see FIG. 3A).
After PNO="OEE" has been recorded for 9 seconds, the system controller 16 sets the mechanical block 1 to a rewinding mode to rewind the tape to a recording start point of PNO="OEE" and sets the flag 20 to "1", completing the end mark operation.
Thus, PNO="OEE" located in the recording terminal portion of the program and representing the read-out area is recorded on the tape, as illustrated in FIG. 3A, and further, the flag 20 stored within the system controller 16 is set to "1", indicative of the detection of the read-out area.
The end search operation is an operation for searching for PNO="OEE" (read-out area) representing the recording terminal portion of the program recorded on the tape, as described before. This operation is normally a processing operation executed prior to the TOC renumbering operation.
When a command for the end search operation is provided from the input device 17, the system controller 16 clears the internal flag 20 (="0").
Next, it is judged whether the present position of the tape is an unrecorded portion or not. In the case of an unrecorded portion, a rewinding running mode is set, and in the case of a recorded portion, a rapid traverse (cue) mode is set. When PNO="OEE" indicative of the read-out area is detected in the respective running modes, the tape is rewound until the recording starting point where PNO="OEE" is reached, whereupon the flag 20 is set to "1" and the operation of the mechanical block 1 is stopped, completing the end search operation.
Thus, the flag 20 is set to "1", indicative of the detection of the read-out area.
The renumbering operation will now be described with reference to the explanatory diagram of FIGS. 3A-3D.
As shown in FIG. 3A, program numbers (PNO) "01" and "02" are assumed to be recorded on the magnetic tape 2 in an overlapping state. Further, absolute time (A-TIME) data t.sub.1 to t.sub.5 at the recording starting point of each program are used as collected TOC information, as illustrated in FIG. 3D.
When the system controller 16 receives a renumbering command from the input device 17, it is first checked whether the above-mentioned flag 20 is set to "1". When the flag="0", i.e., when the renumbering command is not instructed subsequent to the above-mentioned end mark operation or end search operation, the processing mode employed is the normal renumbering operation whereby only the PNO is aligned and rewritten in sequential order.
On the other hand, when the flag="1", i.e., when the renumbering command is issued subsequent to the above-mentioned end mark operation or end search operation, the processing mode employed is a so-called TOC renumbering operation in which TOC information is also written at the same time the renumbering operation is performed.
Namely, as in the operation during TOC renumbering as shown in FIG. 3C, the system controller 16 controls the mechanical block 1 so as to rewind the magnetic tape 2 until a beginning end portion thereof (BOT) is reached. At this time, a counted PNO value held by a counter (not shown) within system controller 16 is reset to "00". Subsequently, the system controller 16 controls the mechanical block 1 to set it to a search running mode in which a STart-ID (ST-ID) recorded in a music top position of each program is searched for.
When the system controller 16 detects the ST-ID of the first program, a value of "1" is added to the counter value of the above-mentioned PNO counter, thereby producing a PNO count value of "01". Thereafter, the counted value "01" is outputted as the PNO of the music program to the signal processing circuit 13, and the PNO and ST-ID are rewritten for the prescribed 9 seconds while the signal processing circuit 13 is operated in an after-recording operating mode. Simultaneously, the system controller 16 stores as TOC information in the memory 19 A-TIME data t.sub.1 (see FIG. 3D) at the recording start point of the program as determined by counting the number of rotations of the rotary drum (the number of frames).
After the above-mentioned PNO and ST-ID have been rewritten for the prescribed 9 seconds, the system controller 16 transmits "OAA", indicative of an invalid PNO, to the signal processing circuit 13 in order to prevent the PNO of the previous program from being incompletely erased, and the value "OAA" indicative of the invalid PNO is subsequently written to the signal processing circuit for 2 seconds, thereafter stopping the after-recording operation. The above-mentioned renumbering operation and the collection of the TOC information are repeatedly executed with respect to each program from the beginning end to the terminal end (EOT) of the tape, as shown in FIG. 3C.
By the above operations, all of the PNOs from the tape beginning end to the tape terminal end are rewritten as continuous numbers according to the sequentially recorded order of the program, as indicated by "01" to "05" in FIG. 3B. Simultaneously, A-TIME data t.sub.1 and t.sub.5 at the recording starting point of each program are collected as TOC information and stored in the TOC information memory 19, exemplary specific values being shown in FIG. 4.
When the renumbering operation for all the PNOs and the collection of the TOC information have been completed from the beginning end to the terminal end of the tape, the processing mode is changed to the recording operation for the TOC information.
The system controller 16 rewinds the tape until the beginning end (BOT) is reached, then searches for the first program recorded on the tape, i.e., the program having PNO="01".
When the search for the above first program has been completed, the system controller 16 outputs "01" as the PNO and starts the after-recording of the PNO for 9 seconds again. Simultaneously, A-TIME data t.sub.1 to t.sub.5 for each program stored in the TOC information memory 19 are written as TOC information to the subcode region for the program of PNO="01" for 9 seconds, completing the TOC renumbering operation.
When the above TOC renumbering operation has been completed, as shown in FIG. 3B, the PNOs of all programs recorded on the magnetic tape 2 are rewritten as a continuous sequence of numbers according to the sequentially recorded order of the programs such as "01" to "05" from the beginning end to the terminal end of the tape, and A-TIME data t.sub.1 to t.sub.5 at the recording start point of each program are recorded as TOC information in the subcode region of the first program (PNO="01") on the tape.
In general, when a cassette is placed in a DAT to reproduce or record a program, the TOC information written in the subcode region of the first program recorded on the tape is automatically read, and thereafter a search, etc., is performed at a high speed based on the read TOC information.
However, in a conventional DAT, when a new cassette is loaded, the TOC information is automatically read irrespective of the state of a tab provided for preventing the unintentional erasure of the cassette. Further, the TOC information is automatically read for use in searching, etc., even in the case of a so-called overwritable cassette in which the erasure-preventing tab is set to the recordable state. Therefore, when the subcode information is added and erased after the TOC information has been read from a cassette in which the erasure-preventing tab is set to the recordable position, the TOC information read when the cassette is first loaded is not coincident with the subcode information actually recorded on the tape, thereby causing problems in the subsequent search operation, etc.
The present invention further relates to a jump method for selecting designated music programs recorded on a tape for a magnetic tape recording and reproducing apparatus, particularly a DAT, in which the operator can easily be informed of the music selecting operation in accordance with information recorded on the tape when a jump selecting operation is performed.
Another example of a conventional type is shown in FIG. 5.
In this figure, reference numeral 31 indicates a mechanical block, and reference numeral 32 a rotary drum carrying magnetic heads 32a and 32b. Reference numeral 33 indicates a tape cassette containing a magnetic tape 33a; 34, a pinch roller; 35, a capstan shaft; 36, a supply reel; and 37, a winding reel.
Further, reference numeral 38 depicts a head amplifier for amplifying a signal reproduced by the magnetic heads 32a and 32b; 39, a subcode reproducing circuit for reading subcode data from the reproduced signal from the head amplifier 38; 40, an ST-ID detecting circuit for detecting an ST-ID (Start ID), i.e., a code representing a starting portion of a music program and music partition portion, from the subcode data from the subcode reproducing circuit and thereby transmitting an output indicative thereof; 41, a counter for counting the number of ST-IDs from the ST-ID detecting circuit; 42, a system control section for controlling various operations as described later; 43, an operating switch for inputting a music program jump number; and 44, a memory for storing the music program jump number for the system control section 42.
The operation of the above-described apparatus will now be described with reference to the flowchart shown in FIG. 6. First, when a music program jump number is inputted to the system control section 42 by the operating switch 43 (step S1), the system control section 42 operates the mechanical block 31 at a high speed (step S2). In the high speed operation, magnetic heads 32a and 32b read subcode data, which is reproduced by the subcode reproducing circuit 39 through the head amplifier 38. The music program jump number inputted by the operating switch 43 is stored in the memory 44 through the system control section 42.
When the ST-ID is present in the subcode data reproduced by the subcode reproducing circuit 39, the ST-ID detecting circuit 40 detects the ST-ID, and its detection output is counted by the counter 41 (step S3). Then, the system control section 42 judges whether or not the count value of the counter 41 is coincident with the music program jump number stored in the memory 44 (step S4). When the count value is not coincident with the music program jump number, the operation returns to step S3 and, when the counter value is coincident with the music program jump number, the mechanical block 41, which has been operating at high speed, returns to a normal reproducing state, the reproduction of the selected music (step 55) is started, and all required operations are completed.
With respect to the display effect for the jump operation in the conventional apparatus described above, even when several music programs are to be jumped, only the numbers of the programs to be jumped are displayed, and there is no display as to what music program number is being searched, which is confusing to the operator.
Further, it is possible that the detection of the desired ST-ID is missed in the jump selecting program and that detection is performed in error due to noise, etc., and a music program different from the selected music program is reproduced.